Conventional devices for the intravenous drip are generally not provided with automatic stopping devices, one must take care whether the medical solution is going to run out or not to stop dripping lest air should flow into the patient's vein.
An automatic stopping device is known provided in the dripping vessel, which can float on the solution level and fall down with it when the solution is going to run out. But the float is round and rather hard to make. Especially its material should have a proper weight and a buoyancy such as plastics. This known float is assembled with two half balls with a circumferential connecting line so the function of stopping solution cannot be completely accomplished. This product, therefore, could hardly be commercially successful.
Besides, all the known solution bottles contain an air tube which is to be pricked through by a needle in order to let the solution drip down into the dripping vessel. This air tube should be made to have its top end to protrude above solution level after said bottle is hung upside down, as otherwise the solution can never drip down smoothly. Consequently it is rather a complicated job to provide the solution bottle with said air tube.